In recent years, the electronics industry has looked increasingly to so-called "stacking" of chip carriers and the like to meet information density requirements. Such practice, wherein plural packages overlie common printed circuit board (PCB) real estate, provides a doubling or more of information density, for example, memory capability.
Known efforts in this area, preceding that set forth in copending commonly-assigned application Ser. No. 85,767 filed on Oct. 17, 1979, had looked to the stacking of chip carriers and dual-in-line packages (DIP) and had provided receptacles having contacts insertable in PCB apertures for soldering thereto and extending upwardly from the PCB to frictionally receive and engage contacts of packages inserted into the receptacles.
Where it was desired to employ the stacked packages electrically independently of one another, the art preceding the '767 application had looked to several measures for separately addressing the packages. Typically, the contacts of the stacked packages were vertically aligned and circuit paths to the PCB would be redundant to the stacked packages for contacts thereof not involved in package selection. Thus, a single receptacle contact would engage vertically successive package contacts. On the other hand, a unique circuit path is required from the PCB to each package contact providing selection or activation of a package. In one known prior approach, receptacle contacts were provided with break-away portions, whereby one would interrupt continuity from the PCB to an upper package contact or a lower package contact, despite vertical alignment thereof. In another known prior approach, package selection contacts were led from the receptacle off-board and were thus not available at the PCB as were all other package contacts. In still another prior approach, packages were customized to provide for vertically unaligned select/address contacts.
While stacking presents little user difficulty where the stacked packages are used electrically dependently in parallel circuit relation to the PCB, user difficulty is seen in the alternative situation wherein vertical address/select differentiation is required. In the first known prior approach discussed above, bypassing of one of two vertically aligned package contacts presented a problem in later accessing such bypassed contact from the PCB. Thus, one needed to define another usable circuit path, for example, from the bypassed package contact to an unused package contact and thence to the PCB through a receptacle contact servicing the unused package contact. In the second discussed prior approach, the off-board disposition of address/select package contacts precluded accessing from the PCB. The last noted prior approach required the tailoring of package contact layout to the receptacle contacts and accordingly did not lend itself to standardization permitting commercial package substitution. Finally, all of the known approaches prior to the '767 application adopted frictional contact interfitting and did not meet zer insertion force applications.
The above and related approaches are more specifically identified in the statement filed herein pursuant to 37 CFR 1.97 and 1.98.
In the '767 application, applicants herein set forth a receptacle for supporting electronic packages in stacked relation and providing electrical connection to package contacts without the disadvantages of the prior approaches. Such receptacle has an upstanding housing defining a channel and supports received packages in vertically spaced relation in the channel. Contacts are supported in the housing in vertically spaced relation and in noninterfering disposition with respect to the channel. An actuator is supported in the housing for displacing the contacts from such noninterfering disposition with respect to the channel into engagement with contacts of the packages. As is set forth in more detail below, the '767 receptacle includes movable support means for the upper stacked package and provides selective spacings of contact sets to facilitate accessing of the packages.
The objective of using common PCB real estate for plural packages, as noted above, is reached by the '767 receptacle with zero insertion force and other benefit. The present invention addresses a further enhancement in PCB real estate usage, namely, disposition of electronic components which are accessory to electronic packages stacked in receptacles. As an example of such an accessory component, a decoupling capacitor typically is used for each separate voltage level supplied to a DIP. Presently, such capacitors are disposed on PCBs as sole consumers of PCB real estate, adjacent the DIP which they serve and are connected to PCB strips in turn electrically connected to package receptacle contacts.